Tunnel kiln



T. c. PROUTY ET AL v TUNNEL KILN File ad Nov. 23, 1925 4 Sheets-Sheet 2Jan. 4, 1927."

LEZGWLZO/ 5; Theodore C. 1 /0749 Jan. 4, 1927.

T. c. PRouTY ET AL TUNNEL KILN i Filed Nov 23, 1925 4 Sheets-Sheet simeizoraj;

Jan, 4, 1927.

'r. C..PROUTY ET AL TUNNEL KILN Filed Nov. 23 I 925 4 Sheets-Sheet 427306732506, Theodore C. 1 /13 y Patented Jan. 4, 1927.

UNITED STA-TE s PATENT OFFICE,

THEODORE PROUTY AND WILLIS O. PROUTY, 0F I-I ERMOSA BEACH, CALIFORNIA,ASSIGNORS, BY MESNE ASSIGNMENTS, TO AMERICAN ENCAUSTIC TILING COM- PANY,LTD., OF LOS ANGELES, CALIFORNIA, A CORPORATION" 'OF NEWi YORK.

TUNNEL 'KILN.

Application filed November 23, 1825; Serial No. 70,775.

kiln which wehave invented and which we describe and claim herein areeconomy construction and operation and uniformity in the applicationofheat to all parts of. the" charge being fired. In tunnel kilns ashere-- tofore constructed it has been the practice toload the chargeupon cars which are top of the'charge being fired, and thi-slras' pushedthrough the'kiln, the-kilns formost purposes being of great length ,twoto three hundred feet and more and containing acorrespondingly longtrain of cars loadedwith material being fired. The cars run -u-pon railslaid on the floor of the tunnel. It.is,-of

course, necessary to protect the trucks and they metal structuralelement frames of the cars from the f excessive: heat- -to which theware ca'rried by them is 'subfected, and this isv accomplished byprovid-" j ing the floors of theflat-topped cars witha layer of materialof low'heat conductivity and providing a sand .seal orother formof,

' seal at about the .level of the car-floor be:

. tween the car'and the side walls of the'tun- .nel f, The floor of thecar is'the conveyor" platform and the heat must be'appliedex'clusivelyto the spaceabove the conveyor platform in order to avoidinjury to, the stru'c-' tural elements and running gearbelowJ In manyinstances. it is. necessary'that heatbe' applied below as well as atvthe sidesand heretofore been accomplished by carrying the ware on arefractory floor,elev ated a ove the car-floor, and'supported- 'on openwork through which thelieated air or products of combustion have access"to 1 the space beneath the "ware. In order to affordspace for cars of acapacity that would justify the costofkilns of, thistype used for themanufacture of tile, brick, pottery, sanitary"w-are, ere-,- ithasbeennecessary to makethe lnter or.

s of. the under width of the tunnel "not less than four feet,

to be fired having substantially thesamev cross-sectionalarea..'\Vhethe1 the ware is inclosed in saggers orset in open formationit has been found impossible to impart a uniform temperature throughouta mass of such large crossrse'ctional area. .-The' inequality inheating'isfrequently so great that the shrinkage of ware at the bottomand sides beforelike shrinkage has taken place in the Ware at the topmakes the mass insecure and causes it to topple over; In someinstancesthe tops of the cars, have been given a pitch of a half-inch'toward thecenter in an endeavor to counteract the tendency of the waretotoppleover from thisuneven shrink= agel Furthermore the refractory to )5 ofthe cars are constantly expanding an contracting'. as 'the c ar's movethrough the tun-' .nel andjare taken from the tunnel for unloading andreloading thus necessitating frequent replacement. Theinitial costof-tun nel kilns: of such large dimensions and the large equipment-ofcars constitutes a' heavy item of expense in the manufacture of cefiimicartioles. i

By means of our invention described and claimed herein We; greatlyreduce the initial "cost ofthe kiln. without reducing its capacityproportionately and at. the. same time render possible and practicable amuch moref'uniform heating" of all parts of the 'chargethan has been.possible or practicable in" kilns 10f thetype above described. Our

improved'kiln possesses the further advantage of dividing-"agivenoutputamong several kilns inplace of firing it allin one k ln of the largedimensions heretofore used, thus minimizing the damage consequent uponany irregularity or-accident in they operation of one of the kilns. 7

In our improved kiln the firing chamber through which the ware is movedis provided with'a stationary. fioorto the underside of which the heatedgases have access, this floor in the kiln herein described formingpartof a continuous muffle extending from end to end of the kiln and beingheated at the sides and top as well as at the bottom. The ware to befired is set upon rectangular slabs of a suitable refractory material.Each slab with its charge set on it is laced on an exterior extension ofthe mu e floor. and pressure exerted on it by a plunger moves it intothemuftle and imparts movement to all of the slabs already in themufile, all of them being in contact, edge to edge. The movement of theplunger is timed to give the material the proper time of firing in itspassage through the tunnel. Additional slabs with their charges loadedupon them are introduced by withdrawing the plunger sufliciently to makespace for placing the additional slab upon the exterior extens on of themuflle floor between the last preceding slab and the plunger. By meansof th s con struction, we have eliminated the mltlal cost and theexpense of maintenance of the cars heretofore used in tunnel kilns, andhave at the same -time. made it poss1ble to economically construct andoperate a tunnel kiln of sufliciently small cross-sectional area tosecure uniformity in the heating of different parts of the charge. Whileit might be theoretically possible to construct and oper ate a tunnelkiln of small cross-section with cars of the usual type and might beeconomically possible to do so 1n the manufacture of articles commandinga sufficiently high price, such a kiln would greatly exceed our improvedkiln in cost of constructlon, ma ntenance and operation, and 1n such akiln the ware could be heated from the under side only by supporting iton open work built up on the car floor, thus reducing the usefulcapacity of the kiln to that extent, whereas in our improved kiln heatis applied directly beneath the fioor and communicated "therethrough andthrough the supporting conveyor slab to the ware. In our improved kilnthere is a uniform communication of heat to the ware from all four sidesof the mufiie;

In the drawings: Figure 1 is a side elevation of our 1mproved kiln.

Figure 2. is a. sectional plan new on the broken line A.-A of Figure 1.

Figure 3 is an end elevation, the left-hand part being broken away onthe l1ne B-B of Figure 2.

Figure 4 is a section on the line DD of Figures 1 and 2.

Figure 5 is a fragmentary section on the line C-O of Figure 1.

Figures 6 and 7 show a drive mechanism.

We have shown the kiln in the drawings elevated to a convenient workingheight upon the foundations 1 and I-beams 2.

The mufiles 3 and 4 extend throughout the length of the kiln and areformed'of slabs 5 of refractory material. Between the two mufilcs, whichare parallel, there is a flue space 6 extending longitudinally of thekiln from a point adjacent the charging end E to a connection with flue6' of reduced cross section (Figure 4) which latter leads to the stackF. The construction surrounding the muttles adjacent the charging end ofthe kiln is clearly shown in Figure 2, and in the left-sectional part ofFigure 3. The lower part of the kiln construction is composed of severallayers of brick, six courses being shown in the kiln illustrated. Themufiies are supported upon the upper part of the under-work of brick.Along the inner ad-' jacent sides the muttles are supported upon solidWalls of refractory brick G. At the outer sides the muflies aresupported upon 1 an open work structure of refractory brick or blocks 7,there being free spaces between the members 7 to afford free passage forthe heated gases; The exterior walls 8 of the kiln and also the endwalls are built upon the underwork of brick. Directed into openings inthe side walls of the kiln between the charging end and the high heatchamber 20 we have shown eight burners, 12, 12, 13, 13, 14, 14, 15, 15,four upon each side. The design of the kiln and the featuresconstituting our invention may be adapted to the use of gas, oil orsolid fuel for heating.

Immediately adjacent each of the burner, openings and upon the sidethereof remote from the charging end of the kiln, the lefthand end asviewed in Figures 1 and 2, we

have provided dividing walls 17 which except by means of the centralflue 6. As indicated in Figure 3, the gases and products of combustionfrom the burners pass into and through the openings provided for themand thence beneath the. muflles where they impinge upon the walls G andflow back to the vertical passages 9 and over the tops of the mufilesand through the spaces 11. During this part of their circulation theheated, gases are confined to the spacebetween adjacent cross-walls 17.Upon passing beyond the edge 18 of the part of the partition 17 abovethe mufile the gases enter the center longitudinal flue 6 which conductsthe gases of all the burners toward the stack); D As indicated inFigures 2 and 4, the high heat chamber is wider'than the pre-heatingpart of the kiln. We have shown two burn-- lit) ers, 21, her, and, as mggases and burners 21 circulate beneath the mufiies,

thence pass upward at the outer sides and over the top thereof, whencethey sweep downward into the space between the mutfles and through theopening 22 in the end wall 40 of the high heat chamber to a duct leadingunder one of the mufiles to the stack F as indicated in dotted lines inFigure 2. From the charging end E of the kiln to the end wall 23 of thehigh heat chamber the flue 6 extends from the top of the kiln to thefoundation brick upon which the muffles are supported, as shown inFigure 3. The wall 23 extends across the upper part of the flue 6 anddown to a horizontal partition 24 WlllChBXtGIldS the length of the highheat chamber 20. The flue 6 communicates with the space beneath thehorizontal partition 24 through an opening in wall 23, thus confining.the gases from the pre-heater burners to the space beneath partition 24,designated 6f on Figure 4. The horizontal partir tion 24 terminates atthe end wall 40 of the high heat chamber, and the gases flowing throughthe flue 6' pass through an opening in end wall 40. The gases from thepre-heating burners and the high heat burners thus come together justbeyond wall 40, whence they flow through a duct beneath one of themuflies to the stack F as indicated in dotted lines in Figure 2.

We make the part of the muflies extending through the high heat chamberwider than the end parts as indicated at 26, Figures 2' and 4, for thepurpose of providing extra space .in the high heat zone with a view tominimizing the danger of. the operation of the kiln being obstructed bythe toppling' over of any of the ware in this part of the kiln.

flo r extending through the muflle and restmg on the refractory floorlining between the side flanges 48 thereof. As indicated at 30 inFigures '1 and 2, we provide exterior ex tensions of the tracks formedby the linings 27 in the bottoms of themuflles; These extensions 30 areoutside of thezone of heat and may be constructed of "metal; In chargingthe kiln a plate 28 is laced upon the track 30 at the charging'en of thekiln and then pushed into the muflle, a second plateis then similarlyloaded with ware and In the bottom of the muflies we provide a moved toa position with its edge abutting against the edge of the previouslycharged plate, and this procedure is repeated as rapidly as thepredetermined rate of movement of the charge through the mufile makesroom for the insertion of a new plate with its load of ware at thecharging end. The series of plates in the muflle are moved forward byexerting pressure upon the last plate to be charged, the pressure beingtransmitted from plate to plate through their abutting edges thusimparting movement to the entire series. Pressure may be applied to theconvoyor plates by any suitable mechanism geared to move the ware at theproper rate for the time of firing necessary. We have shown for thispurpose plunger-s 29 which may 'be temporarily withdrawn a sufficientdistance to permit insertion of an additional plate between the plungerand the last previously charged plate, and then again clutched to thegearing by which it is moved forward at the rate necessary to move theseries of plates through the muflie at the proper speed.

.We have found that carborundum is a suitable material for the conveyorplates 28, this material possessing the necessary strength at hightemperatures to transmit through the series of plates the pressure bywhich they are moved, and our investigations also indicate that thefriction is less when the movable plates and the stationary trackbeneath them are not constructed of the same material and for thisreason we prefer to construct the lining 27 forming the track of arefractory material other than carborundum. We have obtained the bestresults by consfructing one of the parts between which the movementtakes place of vitrified mate- 4 than that used in our kiln and therebywholly or partially vitrified. The carborundum plates 28 move over thevitrified floor plates 27 with relatively little friction and wear, andas the floor plates 27 remain at a substantially constant temperaturethey are not subject to deterioration from contraction and expansion dueto temperature changes.

The earborundum plates 28 are not injuriously afiected by the changesoftemperature to I which they are subjected or by the pressure whichthey undergo when moved through the kiln as above described. In startingthe kiln, and sometimes at intervals thereafter, we find it advantageousto provide a .layer of silica sand or quartz powdered to about 16,meshbetween the carborundum plates 28 and thelining 27 in order to reducethe friction, but in operation suflicient powdered material for thispurpose will generally be formed by the abrasive action between theconveyorplates and the lining.

parting movement to the movable floor wherein the drive shaft 50, bymeans of screw 51 fixed thereto, rotates screw gear 52 and shaft 53.Conical clutch member 54 is fixed to shaft 53. Pinion 55 is formed witha co-a eting conical clutch member and is loose on shaft 53 when notclutched thereto by the conical clutch. Hand wheel 56 is screw-threadedon shaft 53 and afiords means for engaging and disengaging the clutch atwill. Pinion 55 meshes with gear 57 which is fixed to shaft 58. Pinion59, fixed to shaft 58, meshes with gear 60, fixed to shaft 61, to whichpinion 62 is also fixed. Pinion 62 meshes with rack 63 which, with itshead 64, formsthe plunger which bears against the last conveyor plate 28and thus moves the series of plates 28 constituting the movable floorof'the kiln. lVhen a new plate with its charge of ware isto beintroduced into the kiln the clutch is released by turning the handwheel 56 and shaft 61 is manually rotated by means of handle 65 onhand-wheel 66 in the reverce direction, thus through pinion 62,withdrawing the rack and its plunger head 64 to make room for theintroduction of an additional conveyor plate 28. Hand-wheel 66 is thenrotated by hand in the directionof the power drive to bring plunger 64against the newly introduced plate 28, then clutch 55-5 4 is engaged bymeans of hand-wheel 56, thus restoring the power drive to operation.

In Figure 1, we have shown two openings 32, 33, which extend through theouter wall 8 of the kiln and through the wall 5 of the muflie. As'shownin Figure 5, sleeves 35 of refractory material are fitted to the alignedopenings in the walls 8 and 5 and extend across the space therebetween.During the operation of the kiln the outer end of the sleeves 35 may beclosed by bricks loosely placed therein. In the event that, because ofdisarrangement of the ware in the muflie or for other reasons, itbecomes necessary or desirable togain access to the interior of themuifle, thebricks may be removed from the openings formed by the sleeves35 and the contents of the mufile may then be manipulated by suitable-implements, the sleeves serving to confine the gaies to the spacebetween the mufiles and exterior Walls and to protect the implementsfrom the direct action of the heat.

What we claim as our invention is:

1. In a tunnel kiln, a stationary floor constructed of vitrifiedmaterial, means for applying heat beneath said floor and conveyor-Ineans above said floor for moving mate- 11:11 to be fired through thetunnel of said iln.

2. In a-tunnel kiln, a stationary floor constructed of vitrifiedmaterial, a movable floor above said stationary floor, means forapplyingheat beneath said stationary floor, and means for moving said movablefloor through said tunnel.

3. In a tunnel kiln, a stationary floor constructed of vitrifiedmaterial, a movable floor comprising a series of plates above saidstationary floor, and means for applying pressure to said plates to movethe same through said kiln.

4. In a tunnel kiln, a stationary floor constructed of vitrifiedmaterial, means for applying heat beneath said floor, a movable floorcomprising a Series of plates above said stationary floor, and means forapplying pressure to said plates to move the same through said kiln.

5. In a tunnel kiln, a muflie having a stationary floor of vitrifiedmaterial, a movable floor resting on said stationary floor, and meansfor moving said movable floor through said mufille.

6. In a tunnel kiln, a plurality of mufiles arranged side by side withspaces intervening between said mufiles and between said mufiles and thetop, bottom and side walls of said kiln, and means for applying heatthrough said/ spaces to -all sides of said mufiies.

7. In a tunnel kiln, a mufile having a stationary floor of vitrifiedmaterial, a movsaid stationary floor,

able floor resting on said muflie and floor being constructed of refractory material, said movable floor comprising a series of plates andmeans for applying pre-fsure to said plates to move the same throughsaid mufile.

8. In a tunnel kiln, a muflie, means for applying heat to both sides andthe top and bottom thereof, and means inside of said mufile for movingmaterial to be fired therethrough, the part of said means within saidmulfile being constructed of refractory materia 9. In a tunnel kiln, amufiie,'means for applying heat to both sides and the top and bottomthereof, a refractory movable floor inside of said muflie and means forsaid floor through said. muflie.

10. In a tunnel kiln, a muffle, means for applying heat to both sidesand the top and bottom thereof, a movable refractory floor inside ofsaid mufile comprising a series of plates and means for applyingpressure to said plates to move the same through said 11. In a tunnelkiln, movable floor above said stationary floor, said floors beingconstructed of different refractory materials, means for applying heatbeneath said stationary floor, and means for moving said movable floorthrough said tunnel.

12. In atunnel 'kiln, a stationary floor, a movable floor comprising aseries of plates above said stationary floor and means for moving astationary floor, a

- above said stationary floor, said floors being constructed ofdifferent refractory materials, and means for applying pressure to saidplates to move the same through said kiln.

14. In a tunnel kiln, a mufiie, a movablefioor inside of said muflie,said floor and the inner bottom surface of said muffle being ofdifferent refractory materials, and means for moving said movable floorthrough said mufiie.

15. In a tunnel kiln, a muffle, a movable floor inside of said muffle,said floor and the inner bottom surface of said muffle being ofdifferent refractory materials, said movable floor comprising, a seriesof plates, and means for applying pressure to said plates to move thesame through said muffle.

16. In a tunnel kiln, a muflie, means for applying heat to the sides,top and bottom thereof, a movable floor inside of said muflie, saidfloor and the inner bottom surface of said muffle being of differentrefractory materials, and means for moving said" floor through saidmuffle.

17. In a tunnel kiln, a muffle, means for applying heat to the sides,top andbottom thereof, a movable floor inside ofsaid mufile comprising aseries of plates, said floor and the inner bottom surface of said mufllebeing of different refractory materials, and means for applying pressureto said plates to move the same through said mufli'e.

18. In a tunnel kiln, a stationary floor, a movable oarborundum floorabove said stationary floor, means for applying heat beneath saidstationary floor, and means for moving said movable floor through saidtunnel.

19. In a tunnel kiln, a stationary refractory floor, a movable floorcomprising a series of c'arborundum plates above said stationary floorand means for applying pres sure to said plates tomove the same throughsaid kiln. I

20. In a tunnel kiln, a stationary floor of vitrified material, amovable floor comprising, a series of carborundum plates above saidstationary-floor and means for apply-.

ing pressure to said plates to move the same through said kiln.

21. In a tunnel kiln, a stationary refractory floor, means for applyingheat beneath said floor, a movable floor com rising a.

series of carborundum plates :1 ve .said stationary floor, and means forapplying pressure to said plates to move the'same through said kiln. f

22. Ina tunnel kiln, a stationary floor of vitrified material, means.for applying heat.

beneath said; floor, a movable floor comprising a series of carborundumplates above said stationary floor, and means for applying pressure tosaid plates to move the same through said kiln.

23. In a tunnel kiln, a muflie, a movable carborundum floor inside ofsaid muffle, and

means for moving said movable floor through said mufile.

24. In a tunnel kiln, amuflie having a stationary floor of vitrifiedmaterial, a mov able carborundum floor inside of said muffle, and meansfor moving said movable fioor through said mufile.

25. In a tunnel kiln, a muflie, a movable carborundum floor inside ofsaid mufile, said movable floor comprising a series of plates and meansfor applying pressure to said plates to move the same through saidmuffle. 26. In a tunnel kiln, a muffle having a stationary floor ofvitrified material, a movable carborundum floor inside of said muffle,

. said movable fioor comprising a series of muffle and means for movingsaid floor ,through said mutlle.

28.- In a tunnel kiln, a muffle having a stationary floor of vitrifiedmaterial, means for applying heat to the sides and top thereof, amovable carborundum. floor inside of said muflie and means for movingsaid floor through said mufile.

29. In a tunnel kiln, a muffle, means for applying heat to the sides,top and bottom thereof, a movable carborundum floor inside of saidmu'flie comprising a series of plates and means for applying pressure tosaid plates to move the same through said muflle. v

30. In a tunnel kiln, a muflle having a stationary floor of vitrifiedmaterial, means for applying'hea-t to the sides, top and bottom thereof,a movable carborun'dum floor inside of said mufile comprising a seriesof plates and means for applyingpressure to said plates to move the samethrough said mufile.

31. In a tunnel kiln, a stationary floor constructed of vitrifiedmaterial, a movable ifloor supported on said stationary floor, a

layer of loose comminuted material between said stationary and movablefloors, .and means for moving said movable floor through said-kiln.

32. In a tunnel kiln, a stationary floor constructed of vitrifiedmaterial, means for applying heat beneath said stationary floor,

' a movable floor supported on said stationary floor, a layer of loosecomminuted material between said stationary and movable floors,-

and means for moving said movable floor through said kiln. v

33. In a tunnel kiln, a stationary floor constructed of vitrifiedmaterial, a movable floor supported on said stationary floor, a layer ofloose comminuted material between said stationary and movable floors,and means for moving said movable floor through said kiln.

34. In a tunnel kiln, a stationary floor constructed of vitrifiedmaterial, means for applying heat beneath said stationary floor,

a movable floor supported on said stationary floor, a layer of loosecomminuted material between said stationary and movable floors, andmeans for moving said movable floor through said kiln.

35. In a tunnel kiln, a stationary floor, a movable carborundum floor.supported on said stationary floor, a layer of loose comminuted materialbetween said stationary and movable floors, and means for moving saidmovable floor through said kiln.

36. In a tunnel kiln, a stationary floor, means for applying heatbeneath said stationary floor, a movable carborundum floor supported onsaid stationary floor, alaye'r of loose comminuted material between saidstationary and movable floors,'and means for moving said movable floorthrough said kiln.

37. In a tunnel kiln, a stationary floor, :1

and means for moving said platesthrough said kiln.

39. In a tunnel kiln, exterior and interior walls with a heating spacetherebetween, said exterior and interior walls having opposedopeningstherein, a tubular housing of refractory material extending through saidopenings and across said space, and removable means for closing theopening through said housing.

40. In a furnace of the class described, a mufiie, a movable floor insaid mufiie, means for moving said floor through said muflle,independently controllable sources of heat coacting with separatesuccessive sections of the walls of said muflle. I

In witness whereof, we have subscribed our names this 5th day ofNovember, 1925.

THEODORE G. PROUTY. WILLIS O. PROUTY.

